Defining high aspect ratio structures with controllable sidewalls in silicon has become increasingly important both in the nanometer and micrometer scale for solar cells, microelectronic devices, and chemical analysis. High aspect ratio micrometer pillars can be used for solar cell investigations while nanometer scale high aspect ratio pillars can enable fundamental investigations in theories of nanopillar stress mechanics, silicon based lasers, and nanoscale electronic devices such as finFETs and chemical sensors. Currently various nanofabrication techniques exist that rely on self assembly or bottom-up processing. Some top-down processing enabling reproducibility in nanofabrication can also be found.
Among further possible applications are mechanical oscillators and piezo-resistive sensors. High aspect ratio nanopillars with diameters between 50-100 nm could prove useful for core-shell type plasmonic resonators while nanopillars with sub-10 nm diameters have shown promising light emission characteristics.